全文获取类型
收费全文 | 1676篇 |
免费 | 47篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 251篇 |
金属工艺 | 22篇 |
机械仪表 | 35篇 |
建筑科学 | 98篇 |
矿业工程 | 10篇 |
能源动力 | 27篇 |
轻工业 | 264篇 |
水利工程 | 8篇 |
石油天然气 | 3篇 |
无线电 | 88篇 |
一般工业技术 | 187篇 |
冶金工业 | 492篇 |
原子能技术 | 2篇 |
自动化技术 | 227篇 |
出版年
2022年 | 30篇 |
2021年 | 36篇 |
2020年 | 17篇 |
2019年 | 23篇 |
2018年 | 29篇 |
2017年 | 30篇 |
2016年 | 36篇 |
2015年 | 30篇 |
2014年 | 45篇 |
2013年 | 111篇 |
2012年 | 65篇 |
2011年 | 90篇 |
2010年 | 85篇 |
2009年 | 69篇 |
2008年 | 83篇 |
2007年 | 79篇 |
2006年 | 88篇 |
2005年 | 76篇 |
2004年 | 50篇 |
2003年 | 43篇 |
2002年 | 43篇 |
2001年 | 31篇 |
2000年 | 25篇 |
1999年 | 30篇 |
1998年 | 33篇 |
1997年 | 28篇 |
1996年 | 31篇 |
1995年 | 31篇 |
1994年 | 33篇 |
1993年 | 20篇 |
1992年 | 16篇 |
1991年 | 11篇 |
1990年 | 14篇 |
1989年 | 18篇 |
1988年 | 20篇 |
1987年 | 22篇 |
1986年 | 17篇 |
1985年 | 27篇 |
1984年 | 19篇 |
1983年 | 17篇 |
1982年 | 9篇 |
1981年 | 17篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1971年 | 5篇 |
排序方式: 共有1724条查询结果,搜索用时 15 毫秒
1.
Bo Jiang Jeffrey L. Brown Jane Sheraton Nathalie Fortin Howard Bussey 《Yeast (Chichester, England)》1994,10(3):341-353
We have identified three yeast genes, KES1, HES1 and OSH1, whose products show homology to the human oxysterol binding protein (OSBP). Mutations in these genes resulted in pleiotropic sterol-related phenotypes. These include tryptophan-transport defects and nystatin resistance, shown by double and triple mutants. In addition, mutant combinations showed small but apparently cumulative reductions in membrane ergosterol levels. The three yeast genes are also functionally related as overexpression of HES1 or KES1 alleviated the tryptophan-transport defect in kes1Δ or osh1Δ mutants, respectively. Our study implicates this new yeast gene family in ergosterol synthesis and provides comparative evidence of a role for human OSBP in cholesterol synthesis. 相似文献
2.
Utilitarian and economic theories of deterrence hold that the relation of the penalty to the misdeed should be irrelevant. In 5 experiments using hypothetical cases, judgments of penalties depended on whether this relation was in kind (IK) or out of kind (OK). When victims were identifiable, IK penalties were higher than OK and preferred to OK. Subjects seemed to confuse penalties and compensation. When there were no identifiable victims (e.g., environmental damage), IK penalties were preferred, but OK penalties were higher. Here, OK judgments were more uncertain, and subjects preferred to err on the side of overpunishing. The results can be explained in terms of overgeneralization of usually useful heuristics. Alternative hypotheses concerning aggression and scale compatibility are rejected. The findings have implications for the setting of penalties in legal cases (e.g., the Exxon Valdez) and for lay theories of punishment in nonlegal settings. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
Jane Pitcher 《Urban Policy and Research》2006,24(1):67-82
This article explores the role of qualitative and collaborative methods when undertaking evaluation research into local community safety partnerships and neighbourhood strategies. It draws on recent examples of research and evaluation studies of regeneration and community safety programmes in a number of cities and towns in England. The discussion is set against the background of the major changes in policy relating to crime and community safety, particularly the introduction of Crime and Disorder Partnerships and their engagement with local communities. The value of qualitative methods in exploring some key questions is discussed, particularly within a collaborative approach to policy research. 相似文献
4.
This paper contextualises, describes and discusses a student project which takes a particular exploratory approach to using
mathematical surface definition as a language and vehicle for co-rational design co-authorship for architecture and engineering.
The project has two authors, one from an architectural and one from an engineering educational background. It investigates
the metaphorical and operational role of mathematics in the design process and outcomes. 相似文献
5.
6.
Jane L.Huynh 《世界电子元器件》2007,(9):121-122
在30至300GHz之间,毫米波测量的应用正在增加。从高数据速率到汽车行业再到射电天文学,灵活的测量解决方案正日益显现出它的优势。在这些应用中,毫米波测量解决方案必须遵守很多规则。例如,探测环境中的晶圆器件表征,或通过波导或同轴接口进行模块测试。解决方案还包括夹具中或自由空间的材料测量,或室外/室内天线测试。[第一段] 相似文献
7.
Sui Lay Xavier Pearce Oana Sanislav Paul Robert Fisher Sarah Jane Annesley 《International journal of molecular sciences》2022,23(9)
Mitochondrial Complex II is composed of four core subunits and mutations to any of the subunits result in lowered Complex II activity. Surprisingly, although mutations in any of the subunits can yield similar clinical outcomes, there are distinct differences in the patterns of clinical disease most commonly associated with mutations in different subunits. Thus, mutations to the SdhA subunit most often result in mitochondrial disease phenotypes, whilst mutations to the other subunits SdhB-D more commonly result in tumour formation. The reason the clinical outcomes are so different is unknown. Here, we individually antisense-inhibited three of the Complex II subunits, SdhA, SdhB or SdhC, in the simple model organism Dictyostelium discoideum. Whilst SdhB and SdhC knockdown resulted in growth defects on bacterial lawns, antisense inhibition of SdhA expression resulted in a different pattern of phenotypic defects, including impairments of growth in liquid medium, enhanced intracellular proliferation of the bacterial pathogen Legionella pneumophila and phagocytosis. Knockdown of the individual subunits also produced different abnormalities in mitochondrial function with only SdhA knockdown resulting in broad mitochondrial dysfunction. Furthermore, these defects were shown to be mediated by the chronic activation of the cellular energy sensor AMP-activated protein kinase. Our results are in agreement with a role for loss of function of SdhA but not the other Complex II subunits in impairing mitochondrial oxidative phosphorylation and they suggest a role for AMP-activated protein kinase in mediating the cytopathological outcomes. 相似文献
8.
Jane Clary Marcus Quigley Aaron Poresky Andrew Earles Eric Strecker Marc Leisenring Jonathan Jones 《Canadian Metallurgical Quarterly》2011,137(3):190-198
Low impact development (LID) strategies are being encouraged in many communities as an approach to reduce potential adverse impacts of development on receiving streams. Many questions exist regarding how well various LID strategies perform in different settings, just as similar questions have been raised regarding performance of traditional stormwater best management practices (BMPs). Whereas historical focus on BMP performance has been water quality concentrations or loads, characterization of volume reduction benefits for both conventional and LID practices is increasingly an objective of researchers and stormwater managers. More than a decade ago, Urban Water Resources Research Council (UWRRC) members worked to develop a set of standardized monitoring and reporting protocols for traditional BMPs and to establish a master database for the purpose of evaluating BMP performance and the factors affecting performance. This effort culminated in the International Stormwater BMP Database (www.bmpdatabase.org), which contains data for more than 360 BMPs and continues to operate as a clearinghouse for stormwater BMP data and performance analyses. During 2008–2009, the International Stormwater BMP Database project expanded to better integrate LID into the database and develop a set of metrics that can be used to characterize BMP performance with regard to surface runoff volume reduction. This paper provides a condensed overview and progress report on the LID-focused effort, including the following topics: (1)?monitoring guidance for LID at the overall site development level, (2)?an overview of recent changes to the International Stormwater BMP Database to better accommodate LID studies, (3)?a summary of LID studies currently included in the database, and (4)?a proposed approach for evaluating performance of LID studies with regard to reducing surface runoff volumes. 相似文献
9.
Stout Julie C.; Paulsen Jane S.; Queller Sarah; Solomon Andrea C.; Whitlock Kathryn B.; Campbell J. Colin; Carlozzi Noelle; Duff Kevin; Beglinger Leigh J.; Langbehn Douglas R.; Johnson Shannon A.; Biglan Kevin M.; Aylward Elizabeth H. 《Canadian Metallurgical Quarterly》2011,25(1):1
Objective: PREDICT-HD is a large-scale international study of people with the Huntington disease (HD) CAG-repeat expansion who are not yet diagnosed with HD. The objective of this study was to determine the stage in the HD prodrome at which cognitive differences from CAG-normal controls can be reliably detected. Method: For each of 738 HD CAG-expanded participants, we computed estimated years to clinical diagnosis and probability of diagnosis in 5 years based on age and CAG-repeat expansion number (Langbehn, Brinkman, Falush, Paulsen, & Hayden, 2004). We then stratified the sample into groups: NEAR, estimated to be ≤9 years; MID, between 9 and 15 years; and FAR, ≥15 years. The control sample included 168 CAG-normal participants. Nineteen cognitive tasks were used to assess attention, working memory, psychomotor functions, episodic memory, language, recognition of facial emotion, sensory–perceptual functions, and executive functions. Results: Compared with the controls, the NEAR group showed significantly poorer performance on nearly all of the cognitive tests and the MID group on about half of the cognitive tests (p = .05, Cohen's d NEAR as large as ?1.17, MID as large as ?0.61). One test even revealed significantly poorer performance in the FAR group (Cohen's d = ?0.26). Individual tasks accounted for 0.2% to 9.7% of the variance in estimated proximity to diagnosis. Overall, the cognitive battery accounted for 34% of the variance; in comparison, the Unified Huntington's Disease Rating Scale motor score accounted for 11.7%. Conclusions: Neurocognitive tests are robust clinical indicators of the disease process prior to reaching criteria for motor diagnosis of HD. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
Li Y Chen X Zhang X Wang K Wang ZJ 《IEEE transactions on bio-medical engineering》2012,59(10):2695-2704
Identification of constituent components of each sign gesture can be beneficial to the improved performance of sign language recognition (SLR), especially for large-vocabulary SLR systems. Aiming at developing such a system using portable accelerometer (ACC) and surface electromyographic (sEMG) sensors, we propose a framework for automatic Chinese SLR at the component level. In the proposed framework, data segmentation, as an important preprocessing operation, is performed to divide a continuous sign language sentence into subword segments. Based on the features extracted from ACC and sEMG data, three basic components of sign subwords, namely the hand shape, orientation, and movement, are further modeled and the corresponding component classifiers are learned. At the decision level, a sequence of subwords can be recognized by fusing the likelihoods at the component level. The overall classification accuracy of 96.5% for a vocabulary of 120 signs and 86.7% for 200 sentences demonstrate the feasibility of interpreting sign components from ACC and sEMG data and clearly show the superior recognition performance of the proposed method when compared with the previous SLR method at the subword level. The proposed method seems promising for implementing large-vocabulary portable SLR systems. 相似文献